Battery testers

[Groucho]

Does anyone have any experience with battery testers, specifically for checking the life of NiMH rechargables? I've seen a number out there, ranging from $3 models with an analog gauge to ones that light up LCDs to show strength.

I think that I have a couple of batteries that are not holding a charge very well, and more frustratingly, I think they got mixed in with my usual battery rotation. On one of my sets of four batteries, I get much worse than usual battery life, while on another set, I'll get a lot, using batteries that we all bought at the same time (a 20-pack of 2500mAh ones).

I want to figure out which are the ones that hold a charge the best and use those first, and if there are some that are particularly low, set those aside for use in things other than my camera.

 

[photo_chick]

I don't think sticking it to your tongue like a 9 volt will work, huh?

(sorry, couldn't resist that one)

Seriously, I have a tester that I think I paid $20 for. It does it's job and works on a ton of diferent battery types. I got it at the local geek emporium.

 

[AbbysFamily]

Consider looking into the La Crosse BC-900.

Its a charger, but also can test batteries, condition, etc.

It can charge at multiple rates and will show you exactly how many mAH were 'put back in' during a normal charge cycle on EACH battery. It will show battery voltages, etc.

I have to say - I'm much more aware of my individual battery quality now that i have this charger!

 

[Groucho]

Interesting... the only downside is that I already have two chargers (Maha C204F and a 1-hour Rayovac). I know that the Rayovac can have a negative impact on battery life, but it has four circuits, unlike the Maha, so I'll still use it sometimes.

I'm most curious if a cheap tester can actually tell you the amount of charge remaining in an NiHM. They seem to claim to, but it almost sounds too easy?

 

[AbbysFamily]

Most cheap testers work by looking at the voltage and guessing at how much juice is there. The only real way to test how many maH are in a battery is to track how much was put in. (Ok, theres a bit more than that - but thats more or less true)..

As for the 1-hour rayovac... Bad idea in so many ways.. (Not that I didn't make that mistake myself).

 

[Groucho]

Yeah, that's kind of what I figured.

Sigh... one more thing to put on the list!

 

[MarkBarbieri]

I'm most curious if a cheap tester can actually tell you the amount of charge remaining in an NiHM. They seem to claim to, but it almost sounds too easy?

I'm not sure why, but equipment that I have that uses Lithium Ion batteries seem be able to track battery power better than those using NiMH. With my NiMH stuff it seems to say full for a long time and then drop off very quickly while the LI stuff seems to follow more of a steady decline.

I'm betting that most testers are really just volt meters in disguise. As the battery drains, it's voltage level drops. The tester on my battery rack just has three little LEDs and each is probably set up to only light if a certain voltage level is reached.

Remember when battery packs came with little built in tester strips? Suddenly they stopped. I guess it was a patent thing and we'll see them again in a few years when the patent expires.

We switched from rechargeables to disposables a while back. It's gotten so cheap to just buy a monsterous pack of AA and AAA batteries that the tiny cost savings of rechargeables is no longer worth the hassle. Of course, I've got another dozen or so devices with their own proprietary rechargeable batteries, but that's another story. I'm still annoyed by the lack of proximity chargers. Why are those darn engineers doing taking so long???

 

[Groucho]

NiMHs do seem to discharge at a non-linear rate, hence my skepticism over how accurate a basic, cheap battery tester could be.

One thing I could try in the meantime is put each battery in my son's little battery-operated Thomas train (which takes a single AA) and time how long before it runs down... but I think the motor sound would drive my crazy first.